Facultad de Química, Departamento de Bioquímica, UNAM, Avenida Universidad y Copilco, México DF 04510, México.
J Exp Bot. 2013 Dec;64(18):5661-71. doi: 10.1093/jxb/ert340. Epub 2013 Oct 14.
The importance of cell proliferation in plant growth and development has been well documented. The majority of studies on basic cell cycle mechanisms in plants have been at the level of gene expression and much less knowledge has accumulated in terms of protein interactions and activation. Two key proteins, cyclins and cyclin-dependent kinases (CDKs) are fundamental for cell cycle regulation and advancement. Our aim has been to understand the role of D-type cyclins and type A and B CDKs in the cell cycle taking place during a developmental process such as maize seed germination. Results indicate that three maize D-type cyclins-D2;2, D4;2, and D5;3-(G1-S cyclins by definition) bind and activate two different types of CDK-A and B1;1-in a differential way during germination. Whereas CDKA-D-type cyclin complexes are more active at early germination times than at later times, it was surprising to observe that CDKB1;1, a supposedly G2-M kinase, bound in a differential way to all D-type cyclins tested during germination. Binding to cyclin D2;2 was detectable at all germination times, forming a complex with kinase activity, whereas binding to D4;2 and D5;3 was more variable; in particular, D5;3 was only detected at late germination times. Results are discussed in terms of cell cycle advancement and its importance for seed germination.
细胞增殖在植物生长和发育中的重要性已经得到了充分的证明。大多数关于植物基本细胞周期机制的研究都处于基因表达水平，而在蛋白质相互作用和激活方面的知识积累较少。细胞周期调控和推进的两个关键蛋白是细胞周期蛋白和细胞周期蛋白依赖性激酶（CDKs）。我们的目的是了解 D 型细胞周期蛋白和 A 型和 B 型 CDK 在玉米种子萌发等发育过程中的细胞周期中的作用。结果表明，三种玉米 D 型细胞周期蛋白-D2;2、D4;2 和 D5;3（根据定义为 G1-S 周期蛋白）在萌发过程中以不同的方式与两种不同类型的 CDK-A 和 B1;1 结合并激活。虽然 CDKA-D 型细胞周期蛋白复合物在早期萌发时比后期更活跃，但令人惊讶的是观察到 CDKB1;1，一种假定的 G2-M 激酶，以不同的方式与在萌发过程中测试的所有 D 型细胞周期蛋白结合。与细胞周期蛋白 D2;2 的结合在所有萌发时间都可检测到，形成具有激酶活性的复合物，而与 D4;2 和 D5;3 的结合则更具可变性；特别是，D5;3 仅在后期萌发时检测到。结果根据细胞周期推进及其对种子萌发的重要性进行了讨论。
